I don't know that they have ever listed a travel time for the route. Nor have they listed the average speed of the train, so you are in 'ball park' territory.
Easiest solution for you is look up the speed of a mag rail train, find the distance between the two points, and divide the distance by the train speed.
Its not going to be percise, but it is the best you can do.
For example. A little google-fu pulled up this baseline info:
Seattle to San Fran = 1300km approx.
Typical Maglev speeds = 270km/hr (503km/h is the current record set in 2003).
So roughly you are looking at 5 hours one way.